Hereinafter, the general technology corresponding to a background of a technical spirit used in the present invention will be described in brief.
In Mobile Internet based on IEEE 802.16, a mobile station is operated in a diversity sub-channel mode that is a general wireless state, and then is operated in a band adaptive modulation & coding (band AMC) mode if a previously set condition is satisfied. The band AMC mode represents an operation mode that the mobile station collects channel quality information (CQI) of a sub-channel which is currently in service and performs data transmission by using a band comprised of a predetermined number of sub-channels which are in excellent state, based on the collected channel quality information.
Therefore, the mobile station collects channel quality information of each sub-channel, which is currently in service, by measuring CQI of a base station while being operated in a diversity mode by default. Also, the mobile station selects four to five best sub-channels among the sub-channels and requests the base station to convert the current mode to the band AMC mode. Then, the base station determines whether to accept the above request in accordance with a policy which is previously set, such as a resource management rule, and accepts conversion to the band AMC mode by transmitting a predetermined acknowledgement (Ack) message to the mobile station.
If a carrier to interference and noise ratio (CINR) is used as the channel quality information, the mobile station reports the CINR of the four to five best bands to the base station, and the base station allocates a band AMC sub-channel to the reported best bands. Afterwards, the mobile station still collects channel quality information of each sub-channel periodically and can report only a difference value from channel quality information of the best bands to the base station.
According to the aforementioned band AMC mode, since bands comprised of better sub-channels than those of an existing diversity mode are used, they are robust to noise and interference of neighboring cells. Also, it is advantageous in that a transmission rate is improved as a coding rate is enhanced.
Meanwhile, the existing band AMC mode has a limitation in that it is performed with respect to only sub-channels of a service base station. However, if the mobile station is located near the boundary of cells, it can receive a signal from a neighboring base station. In this case, if the mobile station shares a frequency band of a sub-channel for the band AMC mode with the neighboring base station, a range for selecting the best band becomes widen. If the same data are received through a sharing channel, they are combined with each other to enhance reliability in transmission. If different data are transmitted and received through the sharing channel, it is advantageous in that transmission efficiency can be enhanced. However, a problem occurs in that a proper procedure of sharing resources with neighboring base stations in a band AMC mode is not disclosed in the current IEEE 802.16 standard.